European Patent Application Publication No. 302 437 (U.S. Ser. No. 380,414, now abandoned discloses a trailer coupling having force measuring cells integrated therein. With one embodiment a force measuring cell is used for determining the load of a trailer. A further embodiment uses one or a twin arrangement of force measuring cells for determining push and pull forces. The force measuring cells are of a type as disclosed in U. S. Pat. No. 4,739,666 which, in principle, consists of a pot-like housing with a piston inserted in the recess thereof forming a narrow gap between the opposing peripheral surfaces and bottom surfaces. The narrow gap is completely filled with elastomeric material which is in contact with a pressure sensor.